Notes  on  making 
Conf  Pam  l2mo  #417 


DTTlD44baZ 


ISrOTES 


ON 


MAKING  SALTPETRE 


FROM 


THE  EAETH  OF  THE  CAVES. 


Bt  major  GEO.   W.   RAINS, 

CORPS  OP  ARTILLERY  AND  ORDNANCE, 

In  charge  of  the  Gunpowder  Department,  C.  S.  A.,  late  of  the  U.  S.  A.,  and  former  Asst.  Prof. 
of  Chemistry,  &c.,  U.  S,  M.  A. 


NEW  ORLEANS: 
PRINTED  AT  THE  DAILY  DELTA  JOB  OFFICE, 

1861. 


The  crude  saltpetre  from  the  caves — called  grongh  salt'petre  in  com- 
merce— requires  to  be  purified  before  it  can  be  used  for  gunpowder,  and 
for  this  purpose  government  has  established  a  refinery  at  Nashville 
capable  of  refining  daily  5000  pounds  of  grough  saltpetre  into  pure 
nitre,  as  white  as  snow%  and  ready  for  the  pow^der  mills.  In  the  exten- 
sive Government  Powder  Works,  now  in  course  of  rapid  erection  in 
Georgia  under  the  direction  of  the  writer,  over  five  tons  of  saltpetre  v/iil 
be  refiued  each  day,  if  required,  and  converted  into  gunpowder. 

ARTICLES    WANTED    TO    MAKE    SALTPETRE    ON 
A   SMALL   SCALE. 

One  ordinary  iron  pot,  for  boiling ;  three  or  four  tubs,  pails,  or 
barrels  cut  off ;  two  or  thi-ee  small  troughs  ;  some  coarse  bags  or  a 
wheelbarrow  to  bring  the  earth  from  the  cave,  and  four  strong  barrels 
with  one  head  in  each — empty  vinegar,  whiskey  or  pork  Ijarrels  are  very 
good— are  about  all  the  articles  required  for  a  small  saltpetre  manufac- 
tory. To  these,  however,  must  be  added  some  ash  barrels  to  make 
potash  lye,  as  it  is  better  that  this  should  be  made  at  the  same  time  and 
place,  the  ashes  from  the  fire  under  the  pot  for  boiling  assisting  in  the 
production . 

HOW  TO  PROCEED. 

First  bore  a  hole  about  the  size  of  the  finger  through  the  head  or  end 
of  each  barrel  near  one  side,  and  fit  a  wood  plug  to  each  hole — then  set 
the  barrels  on  some  pieces  of  timber  near  each  other,  the  heads  down, 
and  the  hole  of  each  projecting  over  the  timber.  Put  some  twigs  into 
the  bottom  of  each  barrel,  and  on  these  place  straw  or  hay  about  half  a 
foot  thick  when  pressed  down  ;  then,  having  brought  some  of  the  earth 
from  the  cave,  and  broken  up  all  the  lumps,  fill  each  barrel  full  without, 
pressing  it  down.  Put  the  plugs  into  the  holes  tightly,  and  fill  up  each 
barrel  with  as  much  water  (hot  water  is  best  m  winter j  as  it  will  hold  ; 
allow  the  whole  to  remain  until  next  day,  then  pull  out  the  i)lugs,  hav- 
ing: placed  a  tub  or  pail  under  each,  and  pour  all  the  water  from  the 
first  barrel  into  the  second  barrel,  and  all  the  water  or  liquor  v/hich 
drains  from  this  1)arrel  must  l)e  poured  on  top  of  the  earth  of  the  third 
barrel,  and  finally  the  liquor  which  drains  from  this  last  barrel  must  be 
poured  into  a  tub  or  other  vessel.  Now  having  previously  made  some 
strong  lye  from  wood  ashes,  pour  a  small  stream  of  it  into  the  tub  and 
scir  it  well  ;  immediately  the  clear  liquor  will  become  muddy,  and  as 
long  as  the  lye  contiimes  to  curdle  or  cloud  the  liquor,  it  must  be  poured 
in  ;  of  course  you  will  have  to  wait  now  and  then  for  the  licjuor  to  settle 
to  see  if  it  requires  more  lye.  No  more  must  be  used  than  is  necessary, 
for  it  not  only  v-astes  the  lye,  but  is  an  impurity  which  the  refinery  must 
afterwards  get  rid  of.  We  will  suppose  that  the  proper  quantity  of  lye 
hns  been  used,  aud  the  liquor  allowed  to  settle  or  drain  through  cloth 
until  it   becouaes  clear  ;  it  is  then  poured  into  the  pot  and  boiled  away 


until  a  drop  taken  up  by  the  end  of  a  stick  becomes  hard  or  solid  when 
let  fall  upon  coldraetal  or  upon  a  plate. 

The  liquor  is  now  to  be  dipped  out  of  the  pot  and  poured  into  a  cloth 
placed  over  a  tub  or  barrel,  and  allowed  to  strain  through  into  the  tub 
below  and  become  cold.  As  soon  as  the  liquor  begins  to  cool,  crystals  of 
snltpctre  will  commence  forming,  and  when  cold  the  liquor  left — called 
mother  liquor — must  be  poured  off  from  the  saltpetre  back  into  the  pot 
with  the  fresh  liquor  for  Iwiling,  as  it  still  has  considerable  saltpetre  in 
it.  There  will  be  found  at  the  bottom  of  the  pot  after  the  liquor  is 
dipped  out,  when  the  boiling  is  completed,  some  earthy  salts  which,  after 
draining,  can  be  thrown  away  as  impurities  ;  if,  however,  some  long 
needle-shaped  crystals  should  be  seen  in  it  when  cold,  it  contains  some 
saltpetre,  and  about  a  quart  of  hot  water  should  be  added,  and  then 
poured  off  after  a  time,  when  it  will  have  dissolved  all  the  saltpetre 
left  among  the  earthy  salts  ;  this  wash  water  can  then  be  put  back  into 
the  pot  after  the  impurities  shall  have  been  cleaned  out. 

The  Saltpetre  formed  by  the  foregoing  process  must  be  first  allowed 
to  drain  well,  and  then  placed  on  cloths  stretched  before  the  fire  or  out 
in  the  sun  to  dry  ;  when  the  drying  is  completed,  it  is  to  be  put  into 
sacks  or  barrels,  and  is  ready  to  be  transported  to  the  Government  Agent 
at  Nashville,  Lieut.  M.  H.  Wright,  C.  S.  A.  ordnance  officer, who  will  pay 
for  the  same  on  receiving  the  bills  of  its  shipment  on  the  railroad. 

If  the  crystals  of  saltpetre  are  wet  and  brown,  and  will  not  keep  dry, 
it  is  because  too  much  lye  from  the  wood  ashes  has  been  used  ;  this  can 
be  removed  by  nearly  filliug  a  tub  or  barrel  with  the  saltpetre  and 
pouriug  cold  water  on  it,  as  much  as  the  tub  will  hold,  and  after  remain- 
ing about  one  hour,  the  water  can  be  drained  off  from  the  bottom,  when 
it  will  carry  with  it  most  of  the  lye  ;  this  wash  water  must  be  poured 
iuto  the  lye  of  the  wood  ashes  so  as  not  to  lose  the  saltpetre  which  it 
contains. 

The  foregoing  process  evidently  contains  all  that  is  required  in  prin- 
ciple for  the  making  of  Saltpetre  on  a  large  scale,  since  nothing  more  is 
to  be  done  than  to  increase  the  number  of  barrels  and  boilers.  Casks 
would  be  better  perhaps  than  barrels  in  such  case,  and  vats  made  by 
placing  the  lower  ends  of  pieces  of  plank  about  four  feet  long  into  a 
trough,  and  opening  or  spreading  out  the  upper  ends  about  three  feet, 
then  making  ends  to  the  vat,  is  an  economical  and  convenient  arraage- 
ment,  which  may  be  used  on  a  small  as  well  as  a  large  scale,  instead  of 
casks  or  barrels.  In  making  use  of  these  vats,  strips  of  wood  should  be 
placed  over  the  edges  of  the  planks  on  the  inside,  and  a  thick  layer  of 
twigs  and  straw  should  be  placed  at  the  bottom  between  the  planks  on 
the  inside,  as  well  as  along  the  sides  and  ends  to  about  one  foot  of  the 
top  of  the  vat,  and  kept  there  by  pieces  of  wood  leaning  against  the 
sides,  whilst  it  is  filled  with  earth  from  the  cave  ;  if  this  is  not  done,  the 
liquor  will  in  many  cases  drain  through  very  slowly,  and  time  lost  to  no 
purpose.  A  hollow  cr  channel  about  a  foot  deep  should  be  made  along 
the  centre  of  the  earth  in  the  vat,  to  collect  the  water  poured  in. 

Whether  vats,  casks  or  barrels  be  uied,  the  same  principle  must  be 


6 

carried  ont  of  passiug  the  leached  (or  drained)  h'qnor  from  the  first  ves- 
sel into  the  second,  and  from  the  second  to  the  third  before  boilmg, 
otherwise  there  will  be  much  time  and  fuel  lost  in.neleas  boding  of  a 
weak  liquor  ;  this  is  a  common  error  at  the  caves,  and  causes  the  salt- 
petre to  cost  more  than  is  necessary  in  time,  labor  and  fuel. 

We  will  now  follow  the  process  of  leaching  more  particularly.  Sup- 
pose it  takes  eight  gallons  of  water  to  fill  up  the  barrel  after  the  earth 
has  been  put  in  even  with  its  top,  or  nearly  so,  then  about  oue-half  or 
four  gallons  onlv,  will  drain  off,  generally  ;  we  must  now  refill  the  bar- 
rel with  four  gallons  more  of  water,  and  this  time  four  gallons  will  dram 
or  leach  out,  because  the  earth  has  already  been  charged  with  water. 
Again  we  refill  the  barrel  the  third  time,  putting  in  four  gallons  of  water 
more,  and  after  four  gallons  of  liquor  (or  as  much  as  will  drain  away) 
has  again  leached  off,"the  earth  must  !)e  thrown  out,  and  the  barrel  re- 
filled with  fresh  earth  from  the  cave. 

It  .will  now  be  explained  how  to  proceed  so  as  to  have  a  regu- 
lar rotation  of  the  barrels,  as  they  shall  be  emptied  one  after 
the  other  of  the  old  earth  and  refilled  with  fresh  earth  from  the 
cave.  It  will  be  supposed  at  first  that  the  work  is  on  a  small  scale, 
then  there  •  will  be  required  four  barrels,  if  it  be  desired  to  proceed 
economically;  to  make  it  clear,  we  will  suppose  that  these  four  bar- 
rels are  placed  round  in  a  circle  near  each  other,  and  three  of  them 
are  filled  with  fresh  earth,  the  fourth  remaining  empty.  Now  when 
the  earih  of  the  first  barrel  has  been  exhausted  of  saltpetre  by  the  three 
washings,  it  will  be  thrown  out,  but  instead  of  filling  up  this  barrel 
with  frcsii  earth,  we  fill  up  the  fourth  or  empty  barrel,  and  this  can  be 
going  on  during  the  leaching.-  Thus  we  have  three  barrels  working  as 
at  first,  the  fresh  barrel  being  the  third  in  the  new  series,  and  receiving 
the  leached  liquor  from  the  one  iK-xt  to  it.  The  fir?^t  barrel  of  the  new 
arrangement,  however,  has  already  been  washed  twice,  before  the  new 
barrel  was  filled  with  earth  ;  hence,  after  washing  it  once  more  with  the 
four  gallons  of  water,  which  it  has  just  received  from  the  barrel  just 
emptied^ — which  quantity  drains  off  and  is  poured  into  the  one  next  to 
it— the  earth  is  removed  and  this  barrel  left  empty.  Barrel  number 
one,  which  we  first,  emptied  of  the  old  earth,  having  now  been  refilled 
with  earth  from  the  cave,  becomes  the  third  in  the  new  arrangement, 
and  so  on. 

Tne  liquor  of  the  first  of  the  three  working  barrels  being  always 
poured  into  the  second  barrel,  and  the  liquor  which  leaches  from  this 
to  be  always  poured  into  the  third  barrel,  and  finally  the  liquor  which 
drains  from  this  barrel  is  to  be  put  into  the  vessel,  where  the  lye  from  the 
ash  barrel  is  mixed  with  it  and  the  whole  allowed  to  settle.  When  the 
liquor  has  become  clear  by  settling  or  being  strained  through  a  cloth,  it 
is  ready  to  be  placed  into^he  kettle  for  boiling  down.  Thus  there  is  a 
continual  rotation  of  the  work  of  the  barrels  without  disturbing  anything 
and  r-onstantly  providing  strong  liquor  for  the  ketth^  to  be  boiled  with- 
out losing  any  saltpetre  in  the  earth  thrown  away.  Ft  will  generally 
take  two'^days  for  the  liquor  tO  drain  off  from  each  barrel,  but  the  timo 


will  vary  with  the  nature  of  the  earth,  as  a  saudy  one  may  take  but  a  few 
hours,  whilst  a  clayey  one  may  take  tliree  or  more  days.  In  this  case  it 
would  be  better  to  mix  sand  with  the  earth,  leached  ashes  or  gravel,  or 
even  hay  or  straw,  than  to  lose  so  much  time.  If  vats  be  made  deeper 
than  a  barrel,  more  time  will  be  required  to  leach  them  oflf,  which,  oi 
course,  is  to  he  avoided,  as  nothing  is  gained  by  taking  two  or  three 
weeks  to  leach  off  a  large  vat,  whilst  the  same  earth  in  smaller  vats  or 
casks  may  be  leached  off  in  two  days. 

With  I'egard  to  mixinsr  the  lye  of  wood  ashes  with  the  liquor  of  the 
third  vat  or  barrel,  the  proper  way  is  to  take  a  certain  quantity,  say  one 
pint  of  the  liquor,  and  put  it  in  a  clear  glass,  then  gradually  add  the  lye 
and  stir  well.  So  Ioulc  as  the  lye  curdles  or  clouds  the  liquor  more  must 
be  added.  When  sufficient  lye  has  been  used,  allow  ihe  liquor  to  settle 
and  become  clear,  then  add  a  few  drops  more  of  lye,  if  it  no  longer 
clouds  the  liquor,  sufficient  has  been  used,  and  if  adding  the  lye  has  been 
done  carefully,  no  more  has  been  employed  than  was  just  necessary  to 
precipitate  the  impurities.  We  will  suppose  one  gill  of  lye  has  been 
used  to  the  pint  of  liquor,  then  it  would  take  eight  gills  or  one  quart  of 
lye  to  eight  pints  or  one  gallon  of  liquor — hence,  knowing  the  number 
of  gallons  of  liquor,  it  is  easy  to  see  at  once  how  many  gallons  of  lye 
must  be  added  without  further  trial 

The  above  experiment  may  he  employed  to  ascertain  if  any  earth 
contains  Saltpetre,  for  if  the  lye  of  wood  ashes  causes  a  curdling,  or 
muddies  the  water  in  which  a  considerable  quantity  of  the  earth  has 
been  mixed,  and  then  drained  olF,  we  may  presume  that  there  is  Salt- 
petre present,  and  the  quantity  will,  in  general,  bt-  in  proportion  to  the 
amount  of  curdling.  A  slight  clouding  of  the  liquor  may  be  produced 
by  other  salts  Ix'ing  present  instead  of  Saltpetre,  but  if  there  is  much 
curdling,  it  is  a  pretty  sure  sign  of  Saltpetre.  If  there  be  any  doubt, 
however,  allow  the  muddy  liquor  to  settle,  then  draw  it  oft*  and  boil  down 
until  it  thickens,  then  dip  a  slip  of  paper  into  it  and  dry  it  well,  touch  a 
coal  of  fire  to  the  paper,  and  if  it  burns  rapidly  and  sparkles,  you  may 
be  sure  Saltpetre  is  present. 

In  making  lye  from  wood  ashes  it  is  well  to  remark  that  the  leaves, 
bark,  branches  and  liml)s  of  the  tree  contain  more  potash  than  the  trunk 
and  that  the  oak  and  ash  are  generally  the  best  woods  to  get  ashes  from, 
in  leaching  the  ashes  a  similar  arrangement  may  be  used,  as  for  the 
Saltpetre  liquor,  that  is,  four  Ijarrels  may  be  used  together  in  the  same 
way,  keeping  three  filled  with  ashes  and  the  fonrth  empty,  and  passing 
the  lye  from  one  to  the  other  as  before  explained.  By  this  means 
stfong  lye  is  always  on  hand  to  be  used,  and  the  Saltpetre  liquor  is  not 
watered  too  much  by  a  weak  lye  which,  lias  to  be  evaporated  away  at  an 
expense  of  fuel  and  labor. 

I  will  now  speak  of  the  economy  of  labor  in  the  operations  :  thus,  if 
the  cave  is  sufficiently  large  and  hght  enough,  or  can  be  lighted  cheaply 
by  fire — the  ashes  of  which  may  be  used — it  is  evidently  cheaper  to 
carry  the  vats  and  Ijoilers  into  the  cave  just  where  the  earth  is,  or  near 
by,  than  to  carry  the  earth  out  in.  bags  to  the  outside  of  the  cave  to  be 


8 

leached.  Again,  it  is  more  economical  to  bring  water  to  the  earth  than 
to  jtake  the  earth  to  the  water,  when  both  are  outside  of  the  cave,  as  is 
sometimes  done,  because  there  is  much  less  weight  of  water  used.  By 
pursuing  the  method  pointed  out  no  time  or  material  is  lost — each  day 
has  its  regular  recurring  operations  to  be  performed — no  surplus  water 
has  to  be  boiled  away,  and  no  lye  is  wasted,  rendering  the  Saltpetre 
impure. 

To  give  some  idea  as  to  the  quantity  of  Saltpetre  that  can  be  made, 
I  will  state  that  twelve  barrels  of  the  earth  of  the  caves  will,  in  general, 
make  not  less  than  one  hundred  pounds  of  Saltpetre,  and  this  will  take 
from  twelve  to  fifteen  bushels  of  ashes. 

If  the  twelve  barrels  are  arranged  in  four  circles  or  rows,  with  an  extra 
or  fourth  barrel  to  each  row,  then  a  barrel  of  the  leached  earth  can  be 
emptied  from  every  other  row  each  day,  (or  two  barrels  a  day)  and  the 
same  number  filled  with  fresh  earth,  thus  in  six  days  the  twelve  barrels 
will  have  been  worked  through,  and  this  can  be  done  by  one  man,  whilst 
a  second  man  boils  away  the  liquor  and  attends  to  the  vats  or  barrels  ;  a 
third  man  can  more  than  supply  the  ashes  used,  and  can  assist  in  filling 
the  barrels.  Thus  in  six  days  we  have  the  labor  of  three  men,  which  is 
abundantly  ample  to  make  over  one  hundred  pounds  of  Saltpetre,  unless 
the  earth  is  difficult  to  be  procured.  If  the  earth  is  richer  than  that 
supposed,  or  if  the  leaching  of  each  barrel  takes  but  one  day,  instead  of 
two,  as  will  frequently  be  the  case,  then  two  hundred  pounds  of  Saltpe- 
tre may  be  procured  in  the  same  time,  but  in  the  latter  case  will  require 
additional  labor.  This  is  at  present  worth  seventy  dollars,  being  the 
price  which  Government  now  pays  for  a  limited  time,  at  thirty-five  cents 
per  pound,  to  encourage  its  production  and  to  remunerate  individuals 
for  first  cost  of  apparatus. 

Those  who  manufacture  Saltpetre  on  a  considerable  scale  will  find  it 
convenient  to  have  two  or  more  casks  or  cisterns  sunk  in  the  earth,  to 
receive  the  mother  liquor  from  the  evaporating  kettle,  where  it  is  left 
for  twenty-four  hours  to  crystalyze  its  Saltpetre. 

In  boiling  the  liquor  from  the  vats  or  barrels,  after  it  has  settled  or 
been  strained  from  the  sediment  formed  by  adding  the  lye,  a  thick  skum 
will  rise  to  the  surface,  which  must  be  skimmed  off,  as  it  forms,  and 
thrown  on  the  top  of  one  of  the  vats,  so  as  not  to  lose 'the  Salpetre  that 
may  be  dissolved  from  it. 

The  bottom  of  the  pot  or  boiler,  after  a  time,  will  become  foul  from 
the  lime  and  earthy  salts  deposited  on  it,  which  can  be  prevented,  if 
thought  necessary,  to  a  considerable  degree,  by  sinking  in  the  kettle  a 
small  pot  with  a  wide  mouth.  The  sediment  will  collect  in  this  pot 
and  can  be  removed  from  time  to  time,  because  the  liquor  remains  com- 
paratively still  within  it  and  allows  the  salts  to  settle,  whilst  the  agitation 
of  the  boiling  prevents  the  sediment  falling  io  the  bottom  of  the  kettle. 

Saltpetre  made  after  the  foregoing  directions  will  not  have  above  five 
per  cent,  of  impurities  ;  but  if  carelessly  made  it  will  have  much  more, 
and  as  these  have  to  be  separated  at  the  refinery,  before  it  can  be  used 
for  gunpowder,  such  Saltpetre  is  not  worth  so  much  to  Government. 


9 

Tasting  the  earth  to  see  if  it  will  yield  Saltpetre  is  not  a  very  accu- 
rate way  of  determining  the  fact,  because  the  lime  Saltpetre  has  less 
taste  than  the  Potash  Saltpetre,  and  the  former  is  the  one  mainly  in  the 
earth,  which  lye  converts  into  ordinary,  or  potash  Saltpetre.  Thi:s 
an  individual  might  be  deceived  into  rejecting  earth  which  may  yield 
a  snfficient  quantity,  if  worked. 

REMARKS. 

In  order  U>  call  attention  to  the  very  consideral)le  loss  sustained  by 
imperfect  working  of  the  earth  of  the  caves,  I  will  state  that  at  a  certain 
cave  in  Georgia,  which  was  examined  by  Professor  Pratt,  of  the  Ogle- 
thorpe University,  who  kindly  furnished  me  with  the  result  of  his 
analysis — it  appeared  that  in  earth  which  actually  contained  not  less,  on 
the  average  than  90  pounds  to  the  barrel — nuich  of  it  containing:  120 
jjounds — only  about  67  pounds  were  obtained.  Thus  one-fourths  at  least 
of  the  entire  amount  of  Saltpetre  was  lost,  or  about  eight  dollars  to  each 
barrel  ;  also,  the  amount  of  labor  employed  was  abundantly  ample  to 
have  obtaiufHl  and  leached,  daily,  twice  the  quantity  of  earth  that  was 
done,  of  which  there  was  sufficient  within  200  yards  of  the  mouth  of  the 
cave  to  furnish  forty-five  thousand  pounds  of  Saltpetre.  Hence  the  loss 
at  this  cave  was  as  follows,  for  each  12  barrels  of  earth  actually  leached 
at  this  time. 

'i'welve  barrels  of  earth  or  90  pounds  of  Saltpetre  lost  to   one 

barrel  leached,  which,  at  35  cents,  amounts  to        -       -       $31  50 

One  quarter  of  the  Saltpetre  lost  to  each  leached  barrel,  or  22^ 

pounds,  at  35  cents,  amounts  to 7   87^ 


Total  lost,       -       $39  37i 

Here  was  an  actual  loss  to  the  proprietor  of  nearly  forty  dol- 
lars ;  thus  be  received  for  each  12  barrels  worked,  obtaining 
67    pounds  only, $23  45 

Should  have  received,  with  proper  working,  with  the  same 
amount  of  labor  and  capital,  in  tlu;  same  time  24  barrels,  or 
180  pounds, $63  00 

The  above  case  is  a  sufficient  demonstration  of  the  necessity  of  pursu- 
ing the  method  laid  down  in  these  notes  for  the  making  of  Saltpetre. 


10 


HOW  TO  REFINE  SALTPETRE. 


ARTICLES  REQUIRED  ON   A   SMALL  SCALE. 

Two  evaporating  kettle  or  sugar  pans  capable  of  containing  about 
forty  gallons  each  ;  one  kettle  or  boiler  holding  not  less  than  twenty- 
five  gallons ;  one  barrel  arranged  with  a  hole  and  ping  at  bottom,  and 
covered  loosely  with  two  thicknesses  of  bagging,  or  coarse  cloth,  at  its 
open  end,  forming  a  bag  for  straining  ;  one  shallow  wooden  trough  six 
feet  long,  three  feet  broad,  nine  inches  deep,  for  cooling  ;  one  wooden 
rake  ;  one  spade  or  shovel,  having  a.  long  handle  ;  one  wooden  straining 
box  or  trough,  three  feet  three  inches  long,  twenty  inches  broad  and  six 
inches  deep,  with  several  small  holes  in  its  bottom — this  box  is  placed  on 
the  top  of  the  long  trough,  at  one  end ;  one  wash  barrel  having  a  second 
bottom  pierced  with  holes  about  three  inches  above  the  true  bottom,  this 
second  bottom  is  to  be  covered  with  coarse  cloth — hetween  the  bottoms 
a  hole  and  plug  are  made  ;  one  cask  to  receive  wash  water  ;  one  cask  or 
barrel  nearly  filled  with  water  to  receive  all  the  refuse  Saltpetre,  and  in 
which  the  old  filtering  cloths  are  th'own  to  dissolve  out  the  Saltpetre  ; 
one  cask  or  large  barrel  to  receive  mother  liquor  ;  one  platform  scale  or 
set  of  steelyards  ;  together  with  some  buckets,  drying  cloths,  &c 

HOW  TO    PROCEED. 

Weigh  out  two  hundred  and  twenty-five  pountls  of  Saltpetre  and  put 
it  into  the  kettle  or  boiler,  with  sixteen  gallons  of  water  ;  light  a  fire 
under  the  kettle  and  let  it  boil — not  too  briskly,  however— for  about  two 
and  a  half  hours,  removing  the  skum  which  rises  to  the  surface,  which 
should  be  thrown  into  an  e'mpty  barrel.  Cold  water  must  be  thrown  in 
occasionally  to  keep  the  liquor  to  the  same  height  in  the  kettle,  for  it 
must  not  be  allowed  to  boil  away.  After  the  boiling  is  finished,  allow 
the  fire  to  die  out,  and  dip  the  liquor — not  allowing  it  to  cool — into 
the  cloth  on  the  top  of  the  straining  barrel,  whence  it  is  allowed  to  run 
into  the  long  cooling  trough  ;  here  it  is  constantly  agitated  by  raking  it 
forwards  and  backwards  by  means  of  the  wooden  rake,  until  it  has  cooled 
down  to  about  blood  heat,  which  will  take  probably  two  hours  oi-  more. 
During  the  time  of  cooling,  large  quantities  of  fine  needle-shaped  crys- 
tals of  nitre  will  form  in  the  liquor,  which  are  to  be  taken  out  by  means 
of  the  long  handled  spade,  and  thrown  into  the  d'-aining  trough  on  the 
end  of  the  cooling  trough.  When  the  liquor  has  sufficiently  cooled 
down,  run  it  off  into  a  cask  sunk  into  the  earth  for  tlaat  purpose,  by 
means  of  a  hole  and  plug  in  one  of  the  lower  ends  of  the  cooling  trongh 


11 

The  crystals  of  nitre  in  the  draining  trough  will  now  commence  look- 
ing white  as  snow,  and  are  to  be  left  to  drain  until  next  day,  when  the 
nitre  is  removed  to  the  washing  barrel,  which  should  be  cut  off  at  such  a 
height  as  shall  be  about  half  filled  with  the  crystals. 

This  barrel  is  then  to  be  gently  filled  with  cdd  water  to  the  top,  and 
allowed  to  remain  one  hour,  when  the  plug  is  taken  out,  and  the  liquor, 
which  is  nearly  saturated  with  nitre — holding  in  solution  all  that  re- 
mained of  the  mother  licjuor — is  allowed  to  drain  off  into  the  cask  kept 
for  that  purpose.  The  nitre  thus  made  is  nearly  pure,  sufficiently  so  for 
nearly  all  purposes,  and  can  be  made  into  gunpowder.  To  make  the 
finest  quality  of  powder,  however,  the  crystals  must  l)e  twice  washed 
before  being  taken  from  the  washing  barrel,  cold  water  being  poured  in 
each  time  until  the  barrel  is  full,  and  after  remaining  one  hour  each  time, 
is  to  be  drawn  off  as  defore,  and  the  nitre  well  drained  and  then  dried  ; 
the  crystals  are  now  entirely  pure,  and  can  be  used  for  the  best  quality 
of  gunpowder. 

The  foregoing  is  the  process,  on  a  much  larger  scale,  pursued  at  the 
Government  Refinery,  under  direction  of  the  writer,  and  is  a  great  im- 
provement on  the  old  process,  taking  only  one-sixth  part  of  the  time  for- 
merly consumed,  and  hence  saving  largely  in  time,  labor  and  fuel.  It 
is,  in  the  main,  the  method  pursued  at  the  celebrated  Government 
Powder  Works  at  Waltham  Abbey,  England.  The  writer  is  now  en- 
gaged in  making  some  experiments  by  which  he  anticipates  the  process 
will  be  considerably  shortened,  thus  enabling  the  Government  Refinery 
to  double  its  daily  product  without  increasing  the  apparatus. 

It  must  be  observed  that  in  recharging  the  boiler  with  Saltpetre,  in 
stead  of  putting  in  the  previous  amount  of  225  pounds,  only  200  pounds 
will  be  used,  because  in  place  of  pouring  in  fresh  water,  as  in  the  first 
case,  we  will  now  make  use  of  16  gallons  of  the  wash  water  from  the 
crystals,  which  holds  about  25  pounds  of  nitre  in  solution. 

This  is  under  the  supposition  that  the  temperature  of  the  wash  water 
is  about  65  degrees  ;  but  if  it  is  colder  than  this,  it  will  contain  less 
nitre,  and  if  the  temperature  be  that  of  freezing,  only  about  nine  pounds 
of  nitre  will  be  found  in  the  16  gallons,  instead  of  25  pounds. 

Where  two  washings  take  place,  I  find  it  much  more  economical  in 
fuel  to  have  a  separate  cistern  to  hold  the  liquor  of  the  second  washino-^ 
which  is  nearly  a  pure  saturated  solution  of  nitre,  and  this  is  used  for  the 
first  washing  in  the  next  process  ;  thus  is  saved  the  evaporation  of  a 
large  quantity  of  water,  which  would  require  additional  evaporating 
pans  and  furnaces.  I  find  no  appreciable  difference  in  the  purity  of  the 
nitre  thus  washed  from  that  produced  by  the  mode  of  washing  "of  Wal- 
tham Abbey. 

That  portion  of  the  wash  water  which  is  not  used  in  the  boiler  with 
the  new  charge  of  Saltpetre,  is  to  be  removed  to  the  evaporating  pans 
with  the  mother  liquor.  In  the  cask  containing  the  mother  liquor  from 
the  cooling  trough,  there  will  be  found  next  day  a  considerable  amount 
of  large  crystals  of  saltpetre,  which  can  be  collected  and  thrown  in  with 
the  grough  Saltpetre.     The  method  of  evaporating  the  mother  Uquor, 


12 

and  crystalizing  its  saltpetre,  is  entirely  analogous  to  that  already  ex- 
plained in  making  saltpetre. 

It  may  be  observed  that  about  a  gallon  of  liquor  should  be  taken  out 
each  day  from  the  waste  cask  and  put  into  the  evaporating  kettle,  whilst 
the  same  amount  of  fresh  water  should  be  poured  iuto  the  cask,  in  order 
to  prevent  the  water  in  this  cask  becoming  saturated  with  the  waste  salt- 
petre which  is  from  time  to  time  thown  into  it,  as  also  what  it  acquires 
from  the  soaking  of  the  filtering  or  straining  cloths,  etc.  When  the  bar- 
rels into  which  the  skimmings  are  thrown  becomes  full,  it  is  to  be  poured 
into  a  cloth  placed  over  the  cask  containing  the  mother  liquor:;  being 
drained,  a  small  quantity  of  hot  water  should  be  poured  over  what  re- 
mains, and  then  the  refuse  may  be  thrown  away. 

If  a  larger  or  smaller  quantity  of  saltpetre  be  refined  than  that  men- 
tioned, then  corresponding  proportions  of  the  saltpetre  and  water  will  be 
employed  ;  thus  in  the  Government  Refinery  at  Nashville,  5000  pounds 
of  the  salt  are  used  with  generally  about  360  gallons  of  water,  which  are 
boiled  together  for  four  hours.  The  amount  of  impurities  shonld  regu- 
late the  amount  of  water  used,  but  this  is  not  of  much  moment  in  small 
refineries. 

REMARKS. 

Refined  Saltpetre  is  not  required  from  the  caves  that  is  done  by  Gov- 
ernment. 

It  was  stated  in  the  body  of  these  notes  that  Saltpetre  should  be 
put  up  in  bags  or  barrels  for  transportation  ;  it  may  also  be  put  up  in 
kegs  or  strong  boxes,  the  latter  being  made  about  two  feet  long  and 
fifteen  inches  square  (section)  well  nailed. 

The  Saltpetre  may  be  sent  to  any  ordnance  agent  that  may  be  conve- 
nient, as  will  be  seen  by  the  advertisement  below. 


]SrOTIOE. 

The  Ordnance  Department,  Confederate  States,  will  pay  thirty-five 
cents  per  pound  for  all  Saltpetre  delivered  be  fore  the  first  of  February, 
1862,  at  any  of  the  following  points  ; 

Capt.  W.  G.  Gill,  Augusta,  Ga.  ;  C.  G.  Wagner,  Military  Store 
Keeper,  Montgomery,  Ala.  ;  Lieut.  M.  H.  Wright,  Nashville  Tenn.  ; 
Capt.  W.  R.  Hart,  Memphis,  Tenn.  ;  Sandford  C.  Faulkner,  Military 
Store  Keeper,  Little  Rock,  Ark.,  and  at  Richmond,  Ya. 

J.  GORGAS,  Lieut.  Colonel, 

Chief  of  Ordnance. 


HoUinger  Corp. 
pH8.5 


